This invention relates to flat display systems and, more particularly, to a flat display system, which permits versatile display of readily discernible patterns.
Heretofore, various types of flat display systems have been known. In one type, independent light emitting elements are arranged in a planar form as in lamp display boards and luminescent diode display systems. In another type of system, a luminescent material is sandwiched between two electrode plates and activated by application of an electric field, as in electroluminescence display systems and plasma display systems. In a further type, a material capable of undergoing changes of light transmitting character, light absorbing character and other optical characteristics by application of electric field is sandwiched between two electrode plates, as in liquid crystal electro-optical display systems, photo-chromic material display systems and cataphoresis display systems. Further, there is a display system comprising a thin film of liquid crystal and means for impressing heat or a magnetic signal to the film.
However, in the afore-mentioned lamp display systems and luminescent diode display systems the display pattern consists of dot-like pattern elements, so that numerical figures, characters and other patterns are quite ambiguous. In order to obtain a more readily discernible display, a number of very fine luminescent elements are required. In this case, however, the control of the elements is complicated. Also, the manufacturing cost is increased, and the system is more prone to troubles.
There is further known, as a flat display system, an X-Y matrix system where numerical figures from 0 to 9 are displayed with seven segments arranged in a form of figure eight. For example, U.S. Pat. No. 3,655,270 discloses a display system in which a nematic liquid crystal is held between a pattern electrode plate, having seven segments insulated from one another, and an opposing electrode plate. This system is simple in construction and readily capable of control of the display. However, the display is limited to numerical figures, and also the shape of the figures displayed is quite ambiguous. Therefore, this system can be used only for special purposes and is not suited for general use.
Further, U.S. Pat. No. 3,322,485 shows a display system where a liquid crystal is held between two electrode arrangements constituting an X-Y matrix, and U.S. Pat. Nos. 3,415,991 and 3,410,999 disclose display systems in which a magnetic memory and lossy elements in an X-Y matrix form are provided adjacent a cholesteric liquid crystal thin film for impressing heat signals on the film. With these X-Y matrix display systems, versatile display of numerical figures, characters and other patterns is possible. However, the display of inclined portions still requires a number of fine pattern elements. This means difficulty of the display control. In other words, in order to obtain a display of readily discernible patterns, a number of fine pattern elements is necessary, which leads to complications of the construction of the display section and drive circuit.